Monoazo dyes



Patented Jam 31, 1928.

UNITEQSTATES KENNETH HERBERT SAUNDERS A m) HAROLD GOODWIN, or MANCHESTER, assrcnoas T" BarrIsH .nyns'ronr' 's' 'CORPORA'1 ION rmrrnp.

, ENGLAND,

No Dz-awing. Application filed Api'il 14, 1927-,"Se i i'a1 No. 183,895, and in Great Britain April17,1926.

This invention -relates'= tothe manufacture of monoazo dyes and is an improvement in or modification of the invention claimedin British-Patent'No. 242,061. r

In this Patent No. 242;061,-"we-have de scribed the manufacture of newazo dyestufis suitable for printin on cotton with mor-r dants, particularly cirome mordants. The first" component eiiiployed 1 is" the sparingly in soluble diazo compound obtained' radar. Fa

l-amino -2'hydroXy-3-carboxynaphthalcne-(isulphonic acid which is prepared by reducing benzene-azo-2 3-hydroxynaphthoic acid and sulphonating the 1-amino-2 3-hydroxynaphthoic acid so obtained. The second components are pyrazolones which couple smoothly and in good yield. Now, as a result of further researches, we have found that the above-mentioned diazo compound will combine with those monoand dihydroxynaphthalene sulphonic acids, containing at least one free coupling position, which can be coupled with diazo compounds, and in particular with those derived from a-naphthol, such as chromotropic acid (1:8 dihydroxynaphthalene-3: fi-disulphonic acid) and dihydroxy S acid (1:8-dihydroxynaphthalene-4-sulphonic acid) The dyestuffs so obtained are black or dark powders yielding red to violet solutions in water, exhibiting a blue-red dichroism. The aqueous solution gives a blue spot on filter paper, becoming redder on addition of hydrochloric acid. In concentrated sulphuric acid, the dye dissolves to a bright blue solution becoming red on dilution. The new dyestufls combine readily with metallic mordants. The shades obtained when printed on cotton range from reddish-blue 40 to bright greenish-blue. The new dyestufls may also be used as mordant colours for W001.

The following examples will serve to illustrate further the nature of the invention, but we do not confine ourselves to them; the parts are by weight.

Example 1.

283 parts of 1-amino-2-hydroxy-3-carboxy-naphthalene-6-sulphonic acid, which is usually isolated in the form of its hydrochloride, is made into a stifli' paste with water and a small amount of crystalline copper sulphate is added. When the copper sulphate has dissolved there is added suddenly a concentrated solution of 70 parts of sodium nitrite and the mixture is stirred cold= until ..-diazotiz-ation isrcomplete- The-inixturesis then :run :into hydrochloric acid and the yetlow diazo compoundiwvhich separates is filtered 'o'fi'l- The diazo'compoundiis then made into;a: paste .with water. and added to' a neu-. tral solution of-3O4Qparts of -a-naphthol-4-:.8- l disulphonicz acid.n:? To this. is then-added a milk of lime containing 120 parts of calcium hydrOXideand thewhole-isstirred at'a'bout 30 C, until the coupling is .complete;' :iThe dyestutf is precipitated by addition of excess of hydrochloric acid, common salt being added if necessary to complete the separation. with salt solution and dried. It gives a reddish-blue shade fast to light and chlorine, when printed on cotton with a chromium mordant. The 'dyestuti' has the probable formula o e solu u H0;S COOH SO gH Example 2.

HOaS SOaH COOH On the other hand 1 S-dihydroxynaphthalene-4-sulphonic acid gives a dvestuff dyeing blue shades and having the probable formula on o n H038 COOH son;

\Vhat we claim and desire to secure by Letters Patent is 1. The manufacture of azo dyes by diazo- The dyestuti' is filtered off, washed tizing 1-amin0-2Yhydroxy 3 7 car-boxynaphthalene-6-sulphohi'c 'aeid and coupling the diazo compound with sulphonated hydroxynaphthalene.

2. The manufacture of azo dyes by dia'zotizing l-amino-2-hydroxy 3 carboxynaphthalene-6-sulphonic acid and coupling the diazo compound with sulphonated dihy droxynaphthalene.

3. The manufacture of azo dyes by diazotizing 1-amino-2-hydroxy3-carboxynaph-thalene-6-sulphonic acid and coupling the'diazo compound with dihydroxynaphthalene sulphonated in the 3.6 position.

4. The manufactureofazo-d es by diazotizing 1-amino-2-hydroxy-6-sul pho 3 naphthoic acid. and couplingthe-diazo compound with It B-dihydfioxlyhaphthalene-Ii: fi-disulphonic acid.

5. As a. new material, a dyestufi having the probable ionmula- HO;S COOH said dyestufi' being a black powder, soluble in water to a voilet solution showing a blue-red dichroism, the aqueous solution giving on filter paper a blue s 0t which becomes redder on addition of hy rochloric acid, and said dyestuff giving in concentrated sulphuric acid :1 bright blue solution becoming red on dilution with water. i

In testimony whereof we afii-x our signatures;

HERBERT SAUNDERS. HAROLD GQO-DWIN. 

